Revert "ALSA: usb-audio: Skip setting clock selector for single connections"

This reverts commit 67794f88.

We need to explicitly set up the clock selector to workaround a problem
with the Behringer mixers. This was originally done in d2e8f641


("ALSA: usb-audio: Explicitly set up the clock selector")

The problem with MOTU M Series mentioned in commit message was fixed in
a different way by checking control capabilities of clock selectors.

Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Link: https://lore.kernel.org/r/20240128132338.819273-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>